The present invention relates to eyewear having replaceable lenses and more particularly, eyewear having removable securement structures to permit insertion and removal of a lens from a frame.
The construction of eyewear requires that lenses be fitted into a pre-formed frame. For prescription eyewear, this is done manually by an optician for each set of eyewear as the lenses must be formed to fit the prescription of the wearer. The lenses are replaceable, so that they can be changed if damaged or if the prescription changes. Accordingly, frames are designed to allow the lenses to be removed and replaced.
One common method of removably securing a lens to a frame is to split the frame and have the resulting frame portions secured by a screw. Therefore, replacing a lens requires removing the screw to open the frame, and replacing the screw once the lens is in place. These screws can become loose over time and the threads in the frame can become stripped, resulting in the lens being displaced from the frame. Alternatively, lenses may be inserted into plastic frames by snapping the lens into the frame. Since the plastic has only a limited amount of pliability, even when heated, the groove in which the lenses are retained cannot be too deep. Therefore, excessive flexing of the frame can cause the lenses to pop out of the frame.
Conventional methods of retaining lenses in frames have various limitations and have found to be unsuitable for safety glasses. Safety glasses are eyewear which may be worn to protect the eyes and are used, for example, during sporting events or during work-related activates. Safety glasses must be able to withstand impacts without the lens separating from the frame. If such separation were to occur, the lens could be forced into the wearer's eye by the impact. Attempts to secure the lenses in safety glasses have resulted in the lens being difficult to remove and replace. This is especially problematic for prescription safety glasses where the lenses may need to be manually inserted and removed a number of times.
Accordingly, it would be desirable to provide an eyewear assembly that securely retains the lenses in the frame, yet allows for easy insertion and removal of the lenses.